Re: LF: Better picture of the 807 based 500kHz TX

["Graham" <g8fzk@g8fzk.fsnet.co.uk>]

lol  well  that config is  for  linear  service  , you should  have the 
screen  fed  via  something like   6.8K  from the  plate  supply  , with a 
0.1 uF decoupling  cap , no regulation  for  class C as  the  screen voltage 
will  vary as the  anode amps / secondary emission changes [ negative 
resistance type of thing] , you need   a   100 ohm  2 watt  resistor , 
shorted   with a over wound  8 turn 10 mm id  coil  directly  to  the  anode 
as   acp , would  normally  have 50/100 ohms  in series  with the  cathode 
as  auto  bias , should  the  drive  fail, or  IA = inf  very  quickly ... 
starts  off  with  orange anodes  by the  wire supports  , then  yellow , 
then  sparks  inside  , then  white anodes  , then  glass  shatters / melts 
= game over   , with  cathode keying  , looking  at  a  big  gap  cw  key !
Happy  days  : )

G..

--------------------------------------------------
From: "Dimitrios Tsifakis" <dtsifakis@gmail.com>
Sent: Tuesday, December 18, 2012 11:46 PM
To: <rsgb_lf_group@blacksheep.org>
Subject: Re: LF: Better picture of the 807 based 500kHz TX

> 2012/12/19 Graham <g8fzk@g8fzk.fsnet.co.uk>:
> > Why the  stabilised  screen  supply ?
> > G..
> It's embarassing. I like the glow of VR tubes! :-)
>
> 73, Dimitris VK1SV